1. Field of the Invention
The present invention relates to a coating machine for applying coating to works and heating the coating applied to the works for hardening.
2. Description of Related Art
In order to decorate products made of rubber, plastic, etc., reduce the sliding resistance thereof, and enhance the wear resistance thereof, coating has been frequently applied to surfaces thereof. And in order to harden the coating, the coated products have been transferred to a hardening oven, and heated therein for hardening.
In order to reduce the sliding resistance and enhance the wear resistance of weather strips, ex. for motor vehicles, a thermosetting coating has been applied to areas of the weather strips, which are adapted to contact vehicle bodies, and hardened with heat (see Publications of unexamined Japanese patent applications Nos. Hei 7-251124, and Hei 7-257178, ex.). And a device for applying a low friction coating to surfaces of the weather strips has been also contemplated (see Publication of unexamined Japanese patent application No. Sho 57-177367, ex.).
For example, as shown in FIG. 1, first, many pieces of long weather strips are placed on a pallet 10. Then, the pallet 10 on which the long weather strips are placed is transferred to a painting booth 12 in a transverse direction, and coating is automatically applied thereto with a spray gun mounted on a robot 14.
Next, the coated weather strips placed on the pallet 10 are transferred to an interior of the hardening oven 16, which is heated to an elevated temperature atmosphere with steam. In the hardening oven 16, a plurality of pallets 10 are arranged in parallel with each other in a vertical direction at spaces and moved with a conveyor from the lower side to the upper side of the hardening oven 16. The coating on the weather strips which are placed on each pallet 10 is hardened during moving in the hardening oven 16.
The pallet 10 which has moved to the upper side of the hardening oven 16, and has completed the hardening process of the weather strips moves in a transverse direction, passes over the painting booth 12, and is transferred to the upper side of a work transfer device 18. The weather strips placed on the pallet 10 are taken out of the work transfer device 18, and only the pallet 10 moves downwardly. Then, new weather strips are placed on the pallet 10 and similar coating cycles are repeated.
The above-described method of placing many pieces of works (weather strips) on the pallet 10, and subjecting the works to spray coating with the robot 14, however, requires a long coating time so as not to be efficient.
After coated, the works (weather strips) are heated in the hardening oven 16 which is in an elevated temperature atmosphere with steam so that it takes a long time to raise the temperature of the works and harden the coating thereon, and consequently, the moving time of the pallet 10 in the hardening oven 16 becomes long. For this reason, in order to increase the hardening efficiency, many pallets have been required so that the hardening oven 16 becomes great to increase the equipment costs.